Moreau scored 11 goals with 16 assists and 87 penalty minutes in 74 games last year and was second on the Oilers with a plus-6 rating. A key penalty killer, the six-foot-two, 220-pound native of Huntsville, Ont., is an assistant captain for the club.
"We are extremely pleased to have Ethan with us for the long term," Oilers general manager Kevin Lowe said in a statement Friday. "Time and again Ethan has proven himself as one of our team's leaders. His commitment to his teammates and the game can be seen every time he steps on the ice.
"He was an integral part of the Oilers' success in last season's playoff drive and we look forward to his continued leadership."
In 469 games since joining the Oilers in a trade with the Chicago Blackhawks on March 20, 1999, Moreau has scored 83 goals with 75 assists and 538 penalty minutes.
He's in his eighth season with Edmonton.